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WIP: Backwards compatibility for Cartesian macros (ngenerate & nsplat) #19

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6 changes: 6 additions & 0 deletions src/Compat.jl
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,12 @@ module Compat

using Base.Meta

if VERSION >= v"0.4.0-dev+3184"
include("ngenerate.jl")
using .CompatCartesian
export @ngenerate, @nsplat
end

if VERSION < v"0.4.0-dev+1419"
export UInt, UInt8, UInt16, UInt32, UInt64, UInt128
const UInt = Uint
Expand Down
141 changes: 141 additions & 0 deletions src/ngenerate.jl
Original file line number Diff line number Diff line change
@@ -0,0 +1,141 @@
module CompatCartesian

export @ngenerate, @nsplat

macro ngenerate(itersym, returntypeexpr, funcexpr)
if isa(funcexpr, Expr) && funcexpr.head == :macrocall && funcexpr.args[1] == symbol("@inline")
funcexpr = Base._inline(funcexpr.args[2])
end
isfuncexpr(funcexpr) || error("Requires a function expression")
esc(_ngenerate(itersym, funcexpr))
end

function _ngenerate(itersym::Symbol, funcexpr::Expr)
prototype = funcexpr.args[1]
body = funcexpr.args[2]
varname, T = get_splatinfo(prototype, itersym)
ex = Expr(:$, itersym)
sreplace!(body, itersym, ex)
if !isempty(varname)
prototype, body = _nsplat(prototype, body, varname, T, itersym)
else
body = Expr(:quote, body)
end
Expr(:stagedfunction, prototype, body)
end

macro nsplat(itersym, args...)
if length(args) == 1
funcexpr = args[1]
elseif length(args) == 2
funcexpr = args[2]
else
error("Wrong number of arguments")
end
if isa(funcexpr, Expr) && funcexpr.head == :macrocall && funcexpr.args[1] == symbol("@inline")
funcexpr = Base._inline(funcexpr.args[2])
end
isfuncexpr(funcexpr) || error("Second argument must be a function expression")
prototype = funcexpr.args[1]
body = funcexpr.args[2]
varname, T = get_splatinfo(prototype, itersym)
isempty(varname) && error("Last argument must be a splat")
prototype, body = _nsplat(prototype, body, varname, T, itersym)
esc(Expr(:stagedfunction, prototype, body))
end

function _nsplat(prototype, body, varname, T, itersym)
varsym = symbol(varname)
prototype.args[end] = Expr(:..., Expr(:(::), varsym, T)) # :($varsym::$T...)
varquot = Expr(:quote, varsym)
bodyquot = Expr(:quote, body)
newbody = quote
$itersym = length($varsym)
Compat.CompatCartesian.resolvesplats!($bodyquot, $varquot, $itersym)
end
prototype, newbody
end

# If using the syntax that will need "desplatting",
# myfunction(A::AbstractArray, I::NTuple{N, Int}...)
# return the variable name (as a string) and type
function get_splatinfo(ex::Expr, itersym::Symbol)
if ex.head == :call
a = ex.args[end]
if isa(a, Expr) && a.head == :... && length(a.args) == 1
b = a.args[1]
if isa(b, Expr) && b.head == :(::)
varname = string(b.args[1])
c = b.args[2]
if isa(c, Expr) && c.head == :curly && c.args[1] == :NTuple && c.args[2] == itersym
T = c.args[3]
return varname, T
end
end
end
end
"", Void
end

resolvesplats!(arg, varname, N) = arg
function resolvesplats!(ex::Expr, varname, N::Int)
if ex.head == :call
for i = 2:length(ex.args)-1
resolvesplats!(ex.args[i], varname, N)
end
a = ex.args[end]
if isa(a, Expr) && a.head == :... && a.args[1] == symbol(varname)
ex.args[end] = :($varname[1]) # Expr(:ref, varname, 1)
for i = 2:N
push!(ex.args, :($varname[$i])) # Expr(:ref, varname, i))
end
else
resolvesplats!(a, varname, N)
end
else
for i = 1:length(ex.args)
resolvesplats!(ex.args[i], varname, N)
end
end
ex
end

isfuncexpr(ex::Expr) =
ex.head == :function || (ex.head == :(=) && typeof(ex.args[1]) == Expr && ex.args[1].head == :call)
isfuncexpr(arg) = false

sreplace!(arg, sym, val) = arg
function sreplace!(ex::Expr, sym, val)
for i = 1:length(ex.args)
ex.args[i] = sreplace!(ex.args[i], sym, val)
end
ex
end
sreplace!(s::Symbol, sym, val) = s == sym ? val : s

# If using the syntax that will need "desplatting",
# myfunction(A::AbstractArray, I::NTuple{N, Int}...)
# return the variable name (as a string) and type
function get_splatinfo(ex::Expr, itersym::Symbol)
if ex.head == :call
a = ex.args[end]
if isa(a, Expr) && a.head == :... && length(a.args) == 1
b = a.args[1]
if isa(b, Expr) && b.head == :(::)
varname = string(b.args[1])
c = b.args[2]
if isa(c, Expr) && c.head == :curly && c.args[1] == :NTuple && c.args[2] == itersym
T = c.args[3]
return varname, T
end
end
end
end
"", Void
end

isfuncexpr(ex::Expr) =
ex.head == :function || (ex.head == :(=) && typeof(ex.args[1]) == Expr && ex.args[1].head == :call)
isfuncexpr(arg) = false

end